1. Field of the Invention
The present invention relates to an adjustable plumbing fitting, more particularly to an adjustable plumbing fitting that may be used to adjust a length of connection between a supply pipe and an inlet pipe.
2. Description of the Related Art
Referring to FIG. 1, an area in a building, home, etc. where a lavatory apparatus 8 is to be installed is provided with a wall pipe 9 that extends out of a wall, and an outflow hole (not shown) formed in a floor of the building, home, etc. and over which the lavatory apparatus 8 is disposed. A control valve 6 guides the outflow of water from the wall pipe 9, and a flush valve 7 guides the flow of water from the control valve 6 into the lavatory apparatus 8.
However, due to differences in relative positioning between the wall pipe 9 and the outflow hole, and/or variations in the dimensions of the lavatory apparatus 8 (e.g., differences resulting from dissimilar brands), it may become difficult or impossible to interconnect the control valve 6 and the flush valve 7. In such a case, it is necessary to use an adjustable plumbing fitting.
Referring to FIG. 2, U.S. Pat. No. 3,273,919 discloses an adjustable plumbing fitting for use between a supply pipe 11 of a control valve and an inlet pipe 12 of a flush valve, in which an end portion of the supply pipe 11 is sleeved over an end portion of the inlet pipe 12. An O-ring 13 is received in a flanged recess 122 formed in the end portion of the inlet pipe 12. A C-shaped metal gripping ring 14, which has a rhombic cross section, is sleeved on the inlet pipe 12 behind the O-ring 13, and abuts against an end face of the supply pipe 11. The gripping ring 14 is slidably disposed on the inlet pipe 12 and is displaced along with the end face of the supply pipe 11 relative to the inlet pipe 12 as the inlet pipe 12 is inserted deeper into the supply pipe 11. Further, a coupling nut 15 having a shoulder 151 is threadedly engaged with an outer surface of the supply pipe 11. When tightened, the coupling nut 15 moves in a direction away from the flush valve, such that the gripping ring 14 is pressed between the shoulder 151 of the coupling nut 15 and the end face of the supply pipe 11. The interaction between these elements is such that the supply pipe 11 is interlocked with the inlet pipe 12.
However, a drawback of this configuration is that the gripping ring 14 is prone to cut into the outer surface of the inlet pipe 12 when the coupling nut 15 is tightened. Further, since only one edge of the gripping ring 14 presses against the inlet pipe 12 of the flush valve, the gripping ring 14 may lose its frictional contact with the inlet pipe 12 if an external shock is received by the plumbing fitting to thereby loosen the connection between the inlet pipe 12 and the supply pipe 11. In addition, a tool must be used to ensure that the coupling nut 15 is fully tightened.
Referring to FIG. 3, U.S. Pat. No. 5,542,718 discloses an adjustable plumbing conduit. A first conical surface 211 is formed at a mating end of a supply pipe 21 of a control valve, and a second conical surface 221 is formed at a mating end of an inlet pipe 22 of a flush valve. When the first conical surface 211 abuts against the second conical surface 221, and a coupling nut 23 is threadedly engaged with an outer surface of the supply pipe 21, an inwardly directed shoulder 231 of the coupling nut 23 abuts against an outwardly extending projection 222 of the inlet pipe 22. By tightening the coupling nut 23, the inlet pipe 22 and the supply pipe 21 are interconnected.
Although the plumbing conduit achieves its intended purpose of interconnecting the supply pipe 21 of the control valve and the inlet pipe 22 of the flush valve, when these elements are repeatedly subjected to a water hammer effect, leakage of water between the first and second conical surfaces 211,221 and, ultimately, between the coupling nut 23 and the supply pipe 21 of the control valve may occur. Furthermore, an adjusting structure (not shown) of this conventional plumbing conduit is complicated and involves many parts.